Berlin 2018 – scientific programme
Parts | Days | Selection | Search | Updates | Downloads | Help
MM: Fachverband Metall- und Materialphysik
MM 21: Topical Session (Symposium MM): Fundamentals of Fracture
MM 21.4: Talk
Tuesday, March 13, 2018, 11:15–11:30, TC 006
Predicting mechanical properties of carbide-metal interfaces from first principles — •Elric Barbé1,2, Chu-Chun Fu2, and Maxime Sauzay1 — 1CEA, DEN, Service de Recherches Métallurgiques Appliquées, F-91191, UPSay, Gif-sur-Yvette Cedex, France — 2CEA, DEN, Service de Recherches de Métallurgie Physique, F-91191, UPSay, Gif-sur-Yvette Cedex, France
The cavity initiation observed in ductile, brittle and intergranular creep damages is often explained by a fracture of interface between carbide and metallic lattices. Understanding the mechanisms of fracture allows the prediction of the cavity density as a function of applied strain, which law strongly affects the damage evolution. This study focuses on interfaces between a metallic matrix (Fe, Ni) and a representative carbide: M23C6 . Surface, interface and fracture energies are calculated via DFT based on chemical potential analysis. Then, interfacial fractures stresses are estimated by the UBER (Universal Binding Energy Relation) model and compared with good correlation to the results of fully-DFT simulations of tensile test carried out using various methodologies. We investigate the dependence of the interfacial mechanical behavior on chemical compositions, crystallographic structures and magnetic orderings. The predicted fracture stresses of coherent interfaces range between 14 and 20 GPa. Then, the effects of some incoherent interfaces are investigated. The resulting critical stress is about two times smaller, which is consistent with experimental observations showing that interfacial fracture rather occurs at incoherent interfaces. Finally, segregations effects are investigated.